Studies this year have focused on the pathophysiology of leydig cell activation in patients with familial precocious puberty, the production rate of cortisol using a new technique employing stably labeled isotopes of cortisol, the development of therapeutic agents for neutron capture mediated receptor specific cell destruction, and the development of specific tests for the evaluation of corpus luteum function. Progress has been made in each area. A "long acting Leydig cell stimulator" has been demonstrated in the plasma of children with familial sexual precocity. The "true" production rate of cortisol has been shown to be less than previously believed, "Carborane" tagged derivatives of CRF and GRF have been developed that retain biologic activity and, for CRF, have been shown to be internalized and have cytolytic activity in an epithermal neutron beam. The response of the corpus luteum to hCG has been characterized in normal women, setting the stage for the application of this knowledge to the evaluation of unexplained infertility.